In a conventional plate-fin type heat exchanger, such as an evaporator, the nozzles or orifices of the distribution tube within the inlet manifold are longitudinally aligned with the passageways or channels in the plate structure. The refrigerant is directly discharged into the channels in such a manner that the refrigerant contacts the cooling surfaces substantially equally between the air stream inlet and outlet sides. It was suggested by Clifton Briner, a co-worker of the herein-named inventors, that calculations indicated an improvement in performance could be expected if the refrigerant distribution was weighted so that more refrigerant contacts the heat exchanger surface which is first contacted by the air stream then by the air stream leaving the heat exchanger or evaporator.
Accordingly, the present invention is directed toward an improved distribution tube orientation for controlling the refrigerant distribution so that more refrigerant contacts the channel walls on the higher temperature air intake side of the heat exchanger than contacts the channel walls on the lower temperature air discharge side.